experiments

Question 1

repeated measure design

s +w

Answer 1

you test each individual in both conditions comparing their performance in both parts of the experiment

Strengths:

1. Participant variables- individual differences are shown, such as intelligence, past experience etc, which could become extraneous variables are kept constant between conditions.
2. Better statistical test- because there is less variation between conditions.
3. Fewer participants- are required because people are used more than once, therefore more economical

Weaknesses:

1. Order effects- such as learning, fatigue or boredom may become constant errors when one condition is done after another, e.g. participant given the same test may do better due to practice
2. Demand characteristics- may be a problem as the participant does both conditions of the experiment, and may guess the aim of the study and act differently.
3. Different tests- may be needed
4. Participants may decide not to return (or may not be available) for the second part of the experiment.(Participant attrition)

Question 2

independent measures design

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Answer 2

you test one group of people in the first condition and a different group of people in the second condition and then compare the two sets of scores.

1. No order effects- as learning, fatigue or boredom don’t influence the second condition, as the participants only participate in one condition.
2. Demand characteristics- less of a problem as participants should be less likely to guess the aim.
3. Same test- can be used, high in reliability
4. Quickest and easiest way of allocating people to groups

Weaknesses:

1. Participants’ variables differ- could become a confounding variable
2. Worse statistical test- can be used because of more variation between conditions
3. More participants- are required because each is used only once and is therefore, less economical.

Question 3

laboratory

s+W

Answer 3

This is conducted under highly controlled conditions. The variable being manipulated by the researcher is the independent variableand the dependent variableis the change in behaviour measured by the researcher.

strengths
•	Can control variables
•	Allow to make statements about cause and effect- involve deliberate manipulation of variable
•	Can be easily replicated and repeated
•	Easy to record and analyse	

weakness
• Not always possible to control variables
• Confounding variables- affect results and give false set of results
• Not ecological valid (not true to real life situations)
• Demand characteristics- participants may know about experiment and try to behave or give responses expected to give
• Ethics- need consent of participants, keep confidentiality.

Question 4

Field: s+w

Answer 4

This is carried out in the natural environment (real world situation). Participants are not usually aware that they’re participating. The independent variable is still manipulated by the researcher.

strengths
•	High in ecological validity
•	Can avoid demand characteristics
•	There is wider variation
•	It’s flexible	

weakness
•	Time consuming
•	Confounding variables
•	Lack of control over variables
•	Not practical
•	Difficult to debrief
•	Ethical issues- difficult to gain consent

Question 5

3) Quasi/Natural:

S and weakness

Answer 5

This is where the independent variable is not manipulated by the researcher but occurs naturally. It is carried out to compare the effectiveness of the two different styles.

strengths
• Not as artificial as laboratory experiments
• High ecological validity
• Common in psychology as they’re ethically and practically the only design that can be used
-Usefulness

strengths
• Harder to establish causal relationships because IV is not being manipulated
• Can’t be replicated
• Ethical problems

Question 6

matched pair design

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Answer 6

This involves using different but similar participants in each condition.

Strengths:
1. Participant variables- are kept more constant between conditions
2. Better statistical tests- can be used because of less variation.
3. No order effects- don’t occur since the participant only participates in one condition.
4. Demand characteristic- less of a problem as the participant only participates in one condition.
Weaknesses:
1. Participants’ variables differ- could never be perfectly matched in every respect
2. Matching participants is time consuming & difficult
3. More participants- are required because each is used only once (less economical).
4. Participants can only be used once
5. May be difficult to identify the right criteria for matching.